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The most spectacular part of the All Blacks' undefeated run in the Rugby Championship have been their tries - more than six per game - plus the offloads and all their other attacking instincts with which they have wrought havoc against Australia, Argentina and South Africa.

But just as important has been their defence. They have conceded only three tries in four tests, and it comes as a genuine surprise when a team manages to get across the line.

For that they have their general hard-working attitude to thank, but also the defensive nous of assistant coach Wayne Smith, who was brought back into the fold before the World Cup and whose work is really now starting to reap benefits.

Their tackle success rate is in the region of 90 per cent - better than any other of their Southern Hemisphere rivals - although it remains to be seen how the absence of enforcer Jerome Kaino against the Pumas in Buenos Aires will affect them a week on Sunday.

For skipper Kieran Read, the attention to detail that Smith brings to his defensive role is crucial.

"He's just had another year to work on his lines and how he wants guys to defend," Read said today before the All Blacks were due to fly from Auckland to Buenos Aires. "We've certainly bought into it more this year, I think. We've had more time together to really enforce it. It's working really well. Defence is pretty crucial across the board to set an attitude and it's shown that our attitude has been really great so far this year."

The Pumas' ability to get inroads around the breakdown during their 57-22 defeat in Hamilton three weeks ago surprised the All Blacks, who will be more aware of the danger this time.

"It will be crucial for everyone, even the tight five, close to the ruck," Read said. "First and foremost it's about making effective tackles against Argentina, they probably got a bit of a roll on and were able to crawl forward an extra three or four metres which stopped us getting set. If we can do that certainly we'll be prepared."

Coach Steve Hansen highlighted the Pumas' success there and said they were likely to try it again.

"They will come there again so we have to make sure we're better at that," he said. "This team is all about improving all the time and trying to get better, and that's an area we can get better at so we're looking forward to it."

Liam Squire and Elliot Dixon, who played 80 minutes for Southland in their 20-16 victory over Bay of Plenty in Invercargill on Wednesday, are the two options to replace flanker Kaino, who has an injured shoulder and will meet the team in Durban for their match against South Africa.

And Hansen said Dixon was in a particularly good frame of mind.

"He's up there jumping around. He's just had a baby boy, his second child, so he's pretty happy at the moment."